Taniguchi does not do sequels. Ever.

I hope he keeps up with his no sequel thing.

I do wonder about the subtitle though. "Lelouch of the Rebellion" may be part one of the story (so it takes up a season). Then "Lelouch [something else]" takes up another season, so as to continue the story (CC plot). It may not even be centred on Lelouch (like you said), but hopefully it will be.